Control C axis for B axis limits

[eddie]

<DIV>


Considering a 5 axis table on table machine. The B axis is limited to 120 degrees of range: -100 and +20. How do I control the rotation of the C axis to keep the machine on the -100 degree side of motion.


For example the tool is machining on the side of the part that requires the B axis to be at -35 degrees. It could do the same machining with the B axis at +35 degrees and the C rotated 180. This is not just positioning. I amcontinuous 5 axis surface machining with a ball nose.


Is there some mill sequence parameter or technique to do this or is it a post thing. I played with the REPOS macro with no success. I know this is a complex topic. That is why I am here.


Thanks</DIV>

 

[turbocharger]

Hi Eddie


This is a postprocessor problem, I don't think that you need to play with REPOS macro. According to your given example, the side of the part could be machined on -35 as well as on +35with 180 degree rotation on C-Axis.


As the limits you defined are -100 to +20, so in the first attempt as the angle comes out +35 the post will automatically check this against the limits you defined, and REPOS macro will show that this is out of the limits of the machine, and will apply second solution, and will generate the angle with in the defined limits of the machine.


If you upload the mfg file, the program you generated and the post files then it will be more helping.


thanks

 

[turbocharger]

Hi Eddie


An other way tokeep the B-axis to -100 degree side is, Let say you set the datum X=0, Y=0, Z=0, B=0, C=0,and the table tilt to +20 side, then simply rotate theC-axis to 180 degree and set the datum, and run the program.


thaks

 

[eddie]

Thanks for the input Turbo. I am somewhat confused by your response thatI do not need theREPOS macrothen it sounds like you describe it to be the exact solution that I need. I suspect that Ijust do not know how to make it work. I may need somesimple step by step how to.


I am not sure I completely understand the second solution either. Eventually, the machining will continue all the way around the part. I can not run the program because it limitsout (B>20)and stops.


I had to trim some fat to get all the files inunder the size limit. If have the time to take a look at this that would be great. There is nothing simple about the milling sequences so take a look and see if you have a simple post solution.


2009-08-31_124804_repose.zip


Thanks,
Eddie

 

[CAMFUN]

Hi there!


Humm... I don

 

[eddie]

<DIV>


Got it! Ok, I revisited the REPOS macro. I am not sure where I went wrong originally but it seems to give me the correct tool path now, withdrawing, repositioning and continuing correctly.


You are correct about the limit warnings in my post. For years our 5-axis machining stayed confined to a narrow angle envelope. It never came up. I also recognize the limitations of repositioning as you describe. Good points.


The tilt of my tool on this job is constrained to clearing adeep, narrow area of the geometry. I used a curve to control the tilt.


Thanks for the discussions guys. It stimulated a solution.</DIV>

 

[CAMFUN]

Hi Eddie,


Glad it worked for you... I alsoenjoyed this high-level discussion...